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Production logging
ABSTRACT: In the wake of the recent events, deep water owners and operators are challenged to provide improved asset integrity monitoring. Also, as offshore deployments go deeper and further it is increasing the burden on subsea power requirements and structures that deliver this needed energy. Hence, subsea power umbilicals need to integrate larger power conductors with longer tiebacks and greater depths. In this paper, a new method of monitoring the stress/strain and temperature events of these power umbilicals is discussed. Aker Solutions and Omnisens have embedded a fully distributed fiber optic strain and temperature sensor within an umbilical. By illuminating the sensor with a DITEST (Distributed Temperature and Strain) Brillouin Optical Time Domain Analyzer, a sensor is demonstrated for manufacturing verification, installation/deployment certification, and continuous integrity monitoring. INTRODUCTION Chevron is interested in maximizing operational efficiency and reducing the risk of failure, accidents, or downtime within their subsea structures. Aker Solutions and Omnisens SA set forth on those directives in the development, integration and validation of a fully distributed fiber optic strain and temperature sensor for a prototype power umbilical. The goals of this project were to incorporate a monitoring system that improves construction validation, provides installation certification and feedback, and allows permanent on-line temperature and strain monitoring of this high power, long tieback, power umbilical in deep water. By using a distributed sensing technique known as Brillouin Optical Time Domain Analysis (BOTDA), Omnisens developed a dedicated fiber optic strain and temperature sensor cable (hereafter referred to as the sensor) that can be directly integrated into the umbilical manufacturing methods developed by Aker Solutions. The embedded fiber optic cable becomes an integral, fully distributed strain and temperature sensor when illuminated by the Omnisens' Brillouin BOTDA known as the DITEST sensing system, capable to monitor very long structures.
- North America > United States > Gulf of Mexico > Central GOM > West Gulf Coast Tertiary Basin > Walker Ridge > Block 759 > Jack-St Malo-Big Foot Field > Wilcox Formation (0.99)
- North America > United States > Gulf of Mexico > Central GOM > West Gulf Coast Tertiary Basin > Walker Ridge > Block 758 > Jack-St Malo-Big Foot Field > Wilcox Formation (0.99)
- North America > United States > Gulf of Mexico > Central GOM > West Gulf Coast Tertiary Basin > Walker Ridge > Block 678 > Jack-St Malo-Big Foot Field > Wilcox Formation (0.99)
Heat Conduction Analysis of Welding Moving Heat Source Problem Using Idealized Explicit FEM
Ikushima, Kazuki (Graduate School of Engineering, Osaka Prefecture University) | Okada, Takashi (Graduate School of Engineering, Osaka Prefecture University) | Itoh, Shinsuke (Graduate School of Engineering, Osaka Prefecture University) | Shibahara, Masakazu (Osaka Prefecture University)
ABSTRACT: Welding is widely used for assembling steel structures such as ships and bridges. Quantitative prediction and effective control are required to minimize residual stress and welding distortion. Heat conduction FE analysis and thermal elastic plastic FE analysis are generally used in welding simulations. However, these analyses have very large computing time and memory consumption that are proportional to the square or cube of the number of degrees of freedom of the analysis model. To accomplish smaller computing time and memory consumption for thermal elastic plastic analysis, we have developed Idealized explicit FEM. In this study, Idealized explicit FEM for the heat conduction analysis is developed and applied to a series of computations for bead-on-plate welding and tandem fillet welding of a large-scale stiffened plate. As a result, it is found that Idealized explicit FEM can reduce the computing time and memory consumption of heat conduction analysis especially for large-scale problems. INTRODUCTION Recently, numerical simulations have been widely used as the performance of computers has been exponentially increased. Using computer simulations, potential problems and their solutions can be found at an early stage in the design process. Then, the numerical simulation can reduce design and manufacturing costs. In manufacturing, welding is essential and widely adopted. However, it sometimes cause the problem on deformation and stress of welded joints. It is thus important to estimate the welding deformation and residual stress by numerical simulations. Numerical simulations based on heat conduction FE analysis and thermal elastic plastic FE analysis are generally used to predict welding residual stress and deformation (Ueda and Yamakawa, 1971, Fujita and Nomoto, 1971). These analyses can simulate the entire process from the beginning of welding to complete cooling. However, both the number of time steps and the computing time become extremely large even if simple models are analyzed.
- Reservoir Description and Dynamics > Reservoir Simulation (0.95)
- Production and Well Operations > Well & Reservoir Surveillance and Monitoring > Production logging (0.35)
A Pseudo-Compressibility Finite Difference Method For Single-Phase Surface Flow Computations
Huang, J. (Ocean Engineering Research Centre, Memorial University of Newfoundland) | Qiu, Wei (Ocean Engineering Research Centre, Memorial University of Newfoundland) | Hally, David (Defence R&D Canada – Atlantic)
ABSTRACT: A numerical method has been developed to compute the viscous ship flow on non-orthogonal curvilinear grids. The single-phase level set method is adopted to capture the free surface, and an eigenvaluebased pseudo-compressibility finite difference method is used to solve the fully-coupled pressure and velocity equations. In this method, the pressure-velocity system is only solved in the water region. The pressure and velocity are extended from the free surface into the air region along the direction of the level set gradients by enforcing the free surface interfacial jump conditions. The turbulence equations are decoupled from the pressure-velocity system but are solved in a similar way by extending the values of the values at the free surface into the air. The level set function is calculated using a simple transport equation followed by a non-conservative reinitialization step. Both steps are decoupled from the pressure-velocity and turbulence equations. The deferred-correction approach is used for all the equations to achieve high-order precision for the convection terms and to minimize the computational cost. Validations have been carried out for the free surface flows around a Wigley hull and a surface combatant model, DTMB 5512. The numerical results are in good agreement with the experimental data. INTRODUCTION Computational fluid dynamics (CFD) has been widely used to predict ship resistance. The methods used for simulating viscous free surface flow can be grouped in two main classes: surface tracking and surface capturing. In a surface tracking method, the grid is moved to determine the configuration of the free surface at next time step. Surface capturing methods solve the flow on a fixed Eulerian grid and use an auxiliary equation to determine the profile of the free surface. Surface tracking methods are limited by their ability to deal with distorted or breaking waves.
- Reservoir Description and Dynamics > Reservoir Simulation (1.00)
- Data Science & Engineering Analytics > Information Management and Systems (1.00)
- Reservoir Description and Dynamics > Reservoir Fluid Dynamics (0.89)
- Production and Well Operations > Well & Reservoir Surveillance and Monitoring > Production logging (0.64)
Measurement of Local Void Fraction of Bubbly Flows Generated By Breaking Waves
Huang, Ching-Jer (Department of Hydraulic and Ocean Engineering National Cheng Kung University) | Lin, Yann-Tesrn (Department of Hydraulic and Ocean Engineering National Cheng Kung University) | Tien, Tsung-Mo (Underwater Technology Section Chung-Shan Institute of Science and Technology)
ABSTRACT: This work presents a novel fiber-optic sensing system to measure the local air-volume (void) fraction of bubbly flows caused by breaking waves near a submerged breakwater. Initially, a sensing system with a single fiber-optic probe is developed to detect the local void fractions of bubbly flows. The rating curve between the time fraction ratio of the bubble signal and the void fraction is then established by performing calibration experiments in a cylindrical tank. The high correlation coefficient between the time fraction ratio and the void fraction suggests that the proposed fiber-optic sensing system can measure local void fractions in the range of 1 % to 16 %. Additionally, based on the proposed system the bubbly flows near a submerged breakwater caused by breaking waves are investigated. Effects of different variables on the distribution of void fraction at the lee side of breakwater are systematically studied. These variables include the incident wave height, period and width of the breakwater. INTRODUCTION Fiber-optic probes have been extensively adopted recently to study bubbly flows (Rinne and Loth, 1996; Hamad et al., 2000; Guet et al., 2003; Juliá et al., 2005; Rojas and Loewen, 2007; Blenkinsopp and Chaplin, 2010). Local air-volume (void) fraction can be estimated by detecting the phase variation at the probe tip. The fiber-optic probe is characterized by its very fine structure, which minimizes the disturbances of a device to a physical field. In the conventional two-phase flow model (Ishii and Hibiki, 2010), local void fractions are defined based on the concept of the gas-phase density function XG(x, t). Where XG equals unity whenever position x is in the air phase at moment t; otherwise XG equals zero. The bubble signature can be identified by examining the phase variation detected by fiber-optic probes.
- Reservoir Description and Dynamics (1.00)
- Production and Well Operations > Well & Reservoir Surveillance and Monitoring > Production logging (1.00)
- Data Science & Engineering Analytics > Information Management and Systems (1.00)
ABSTRACT Wave impact tests were performed in the flume tank of Ecole Centrale Marseille in order to investigate whether bubble curtains could be a relevant solution as an anti-sloshing device on board membrane LNG carriers for low and partial filling conditions, when associated to a sloshing monitoring system. Bubble curtains were generated by bubblers located at the foot of the instrumented wall. Parameters related to the wave generation (focalization or solitons) and to the bubblers (type, location and gas flow rate) were screened in order to measure their influence on the impact pressures. The range of gas flow rates studied was restricted to an economically feasible range at full scale. Whatever the wave generation, the current induced by the bubble curtains favors the overturning of the wave crests and, therefore, accelerates the wave breaking process. The location of the bubblers and the gas flow rate make this process more or less efficient. The variability of the loads is increased and the size of the high loaded areas is reduced. The added compressibility of the aerated water does not seem to be of significant influence. Depending on the advancement of the wave breaking process for an incident wave, the influence of a bubble curtain on the wave impact loads turns out to be either positive or negative. Consequently, bubble curtains are not considered as a relevant principle for designing an anti-sloshing device on board LNG carriers. INTRODUCTION Wave impact tests were performed in the wave channel of Ecole Centrale Marseille (ECM) in 2009, at two different scales (see Kimmoun et al., 2010), in order to study the scaling effects on impact pressures. During this campaign, a preparatory work consisted in enabling the generation of deterministic inflow conditions for the wave impacts at both scales.
ABSTRACT Norströmsgrund lighthouse full-scale data from the winter 2002/2003 shows that ice induced vibrations of a vertical sided offshore structure is occurring more frequently from mid-March and later, than earlier in the winter. Metrological data is used to calculate the ice growth and it is found that the occurrence of ice induced vibrations may correspond with the stop in ice growth. Direct measurements of ice temperature in the surrounding ice cover indicate that the temperature profile in the ice cover changes from a linear shape to a C-shape between 28 February and 10 March. The major observations of ice induced vibrations were done from 10 March and later. Then intense vibrations were detected after a time period with air temperatures in the range of 0°C to +10°C. Ice induced vibrations were also corresponding with occurrence of global ice drift observed from satellite images. INTRODUCTION Ice induced vibrations of vertical faced structures in ice-covered waters has been a known challenge since the first observations of the phenomenon in Cook Inlet Alaska by Peyton (1968). From that time, ice induced vibrations has been observed at full scale structures in Bohai Bay (China), Gulf of Bothnia (Sweden and Finland), Beaufort Sea (USA and Canada), Caspian Sea (Kazakhstan) and Sakhalin Island (Russia). Large steps towards an explanation of the ice induced vibration phenomenon were taken after four decades of research by the latest issue of the ISO code for arctic offshore structures (ISO 19906–2010). Continuing work are ongoing by DNV and others to refine the proposed design guidelines in ISO 19906–2010. During the four decades of research on ice induced vibrations, most attention has been devoted to the in-depth physical (mechanical) description of ice-structure interaction. Sophisticated models have been proposed by Mättänen (2001), Sodhi (1995), Kärnä (2008) and several others.
- North America > United States (1.00)
- Europe (1.00)
- Asia > Russia > Far Eastern Federal District > Sakhalin Oblast (0.24)
- Asia > Russia > Far Eastern Federal District > Sakhalin Island > Sea of Okhotsk (0.24)
- Production and Well Operations > Well & Reservoir Surveillance and Monitoring > Production logging (0.51)
- Facilities Design, Construction and Operation > Offshore Facilities and Subsea Systems (0.34)
Influence of Liquid-Gas Physical Parameters On Severe Slugging In a Pipeline-Riser System
Gao, Song (State Key Laboratory of Ocean Engineering, Shanghai Jiao Tong University) | You, Yunxiang (State Key Laboratory of Ocean Engineering, Shanghai Jiao Tong University) | Li, Wei (State Key Laboratory of Ocean Engineering, Shanghai Jiao Tong University) | Yang, Chi (Center for Computational Fluid Dynamics, College of Science, George Mason University)
ABSTRACT A CFD method is proposed to simulate the gas-liquid severe slugging in a pipeline-riser system in the present paper. Based on the consistence principle of the severe slugging formation condition, the 3D flow in a pipeline-riser system is simplified into a 2D flow. The severe slug flow in a pipeline-riser system with a given pipeline declination angle is simulated numerically. The effects of gas-liquid physical parameters on slug flow characteristics are studied and analyzed when the liquids are water, crude oil and kerosene, and the gas are methane and air, respectively. Numerical results show that physical properties of the liquid, including viscosity, density and surface tension, have remarkable influence on the characteristics of severe slugging, including the flow pattern, the period and the pressure fluctuation, whereas the influence of the gas physical properties on the characteristics of the severe slugging is not significant. INTRODUCTION The pipeline-riser system, including a downward inclined pipeline and a vertical riser, is needed to transport oil (with water) and associated gas from subsea wellheads up to offshore platform systems in the exploitation of offshore oil and gas (Sertã, 2004). At low flow rates of gas and liquid, one important problem experienced in such a pipeline-riser system is a severe slugging phenomenon that is defined as the buildup of liquid slug that equals to or exceeds the riser's height (Schmidt, 1985; Fabre, 1990). This phenomenon, also called terrain-induced slugging, is a considerably harmful flow pattern in offshore petroleum production systems because of its high potential in causing sudden fluctuations of pressure and flow mass in the pipeline and overflow or interruption of the terminal gas-liquid separator (Sarica, 2000). Such a severe slug flow can thus damage the production equipment and greatly reduce the production capability. The gas-liquid severe slugging in a pipeline-riser system has been studied experimentally in several flow laboratories.
- Research Report > New Finding (0.50)
- Research Report > Experimental Study (0.35)
- Production and Well Operations > Well & Reservoir Surveillance and Monitoring > Production logging (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Risers (1.00)
- Facilities Design, Construction and Operation > Pipelines, Flowlines and Risers > Pipeline transient behavior (1.00)
Jumper Analysis With Interacting Internal Two-Phase Flow
Chica, Leonardo (University of Houston, Department of Mechanical Engineering Technology) | Pascali, Raresh (University of Houston, Department of Mechanical Engineering Technology) | Jukes, Paul (MCS Kenny) | Ozturk, Burak (MCS Kenny) | Gamino, Marcus (University of Houston, Department of Mechanical Engineering Technology) | Smith, Kevin (University of Houston, Department of Mechanical Engineering Technology)
ABSTRACT: Flow Induced Vibration(FIV)is one of the important phenomena that contribute to failure of jumpers. A computational study was developed to analyze vibrations caused by slug flow in a rigid M-shaped jumper and to estimate the potential effects on its fatigue life. This fluid-structure interaction(FSI)research was conducted in a two-bend model jumper to determine the stresses and pressure fluctuations and predict its response due to the unsteady multiphase flow. A six-bend (whole) jumper simulation was also performed to analyze flow parameters and pressure fluctuations of an original jumper design. Initially, a risk assessment method was carried out to determine the likelihood of failure (LOF) due to flow induced turbulence. After the screening method, amore detailed FSI analysis of piping vibration and response is recommended, specifically "two-way coupling". This FSI study couples the Finite Element Analysis (FEA) model with the Computational Fluid Dynamics (CFD) model to compare the structural natural frequencies with the slug frequencies and consequently obtain the stress range for fatigue analysis. A conclusion can be drawn that whether assessing FIV fatigue damage should be required for future investigation. INTRODUCTION Subsea production systems require different types of piping to transport fluids between components. A typical piping system in performing this function is a jumper which usually connects a tree with a manifold. Rigid jumpers are standard shaped pipes that can withstand high static and dynamic loads due to internal pressure, temperature and external fluid effects. Internal turbulent flow in pipes is an event in which there is an interaction between the fluid and the structure and this phenomenon has become a great concern in the Subsea industry. It is important to understand the effects of the turbulent flow in the structure since this interaction can generate high amplitude vibrations, also known as "flow-induced vibration".
Study On Influencing Factors of Drag Reduction By Air Layer to a Flat Plate With Bottom Step
Ou, Yongpeng (Department of Naval Architecture and Ocean Engineering, Naval University of Engineering) | Dong, Wencai (Department of Naval Architecture and Ocean Engineering, Naval University of Engineering)
ABSTRACT Air lubrication is a promising idea to reduce hull drag and increase hull speed. Although some applications of this concept has been carried out in several countries, there are still few theoretic studies and numerical simulations concerning to its application on high speed planing crafts, and even fewer systematic investigations to examine the influencing factors when it applied on stepped planing crafts. To elaborate these, a numerical study on drag reduction by air layer at a flat plate with bottom step is then carried out, by using 2D viscid numerical model and Air-Liquid Mixture phase model via Fluent code. Some factors, such as fluid velocity, air injection velocity, step height, stern ramp and air injection location on drag reduction rate and air cavity shape are discussed. It is found that the key factors impacting drag reduction rate are not the air injection velocity but the air flow rate, bottom step height and air inlet location. Fluid velocity has little effect on the non-dimension saturation air flow rate. A long and stable air cavity can be obtained by setting an abrupt step on the lower surface of plate, but the saturation air flow rate is increased as the step height increase up. A stern ramp toward the step rear is beneficial to increase the length and thickness of air cavity. The air cavity is kept to be stable when air inlet location is set in the fluid stagnant area, but it may change to bubble layer while the injection location out of the range. INTRODUCTION Air lubrication is a promising method to reduce hull drag. At present, this conception can be implemented as two approaches. The first one is named Air Bubble Drag Reduction by injecting air bubble into the nearwall region of hull, using the bubble to change the density, viscosity and turbulence model of water, and finally reduce skin-friction (Madavan, 1985; Dong et al., 2002).
- Transportation > Marine (0.54)
- Energy > Oil & Gas > Upstream (0.46)
- Reservoir Description and Dynamics (1.00)
- Production and Well Operations > Well & Reservoir Surveillance and Monitoring > Production logging (1.00)
Experimental Study On Wake Flow of an Inclined Square Cylinder
Lou, Xiaofan (School of Civil and Resource Engineering, The University of Western Australia) | Zhou, Tongming (School of Civil and Resource Engineering, The University of Western Australia) | Cheng, Liang (School of Civil and Resource Engineering, The University of Western Australia) | Hao, Zhiyong (College of Logistics Engineering, Shanghai Maritime University) | Jiao, Hui (School of Engineering, University of Tasmania)
ABSTRACT: This study aims to examine the validity of the independence principle (IP) and the vortex characteristics for a square cylinder with different inclination angles (α) encountering wind flow at Reynolds number (Re) of about 3600. A 1D vorticity probe was used to measure the spanwise vorticity component in a wind tunnel, together with a reference Xprobe located at the edge of the wake to provide a reference signal. By examining the contours of velocity and vorticity components using the phase-averaged method, the dependence of the flow properties on inclination angles was analyzed. The present results show that the three-dimensionality of the wake is enhanced and the vortex shedding strength is weakened with the increase of the cylinder inclination angle. When α is larger than 40°, the IP is no longer valid. The Strouhal number (Stn), obtained using the velocity component normal to the cylinder axis, remains approximately a constant within the experimental uncertainty when α is smaller than about 30ِ, indicating the validity of the IP over this angle range. INTRODUCTION Flows approaching a square cylinder with its front face normal to the streamwise direction have been studied extensively due to its practical and fundamental significance. However, in many engineering applications, the flow approaches the cylinder at an inclined angle. While the flow structures and vortex shedding of an inclined circular cylinder have been reported in a number of researches (e.g. Surry and Surry, 1967; King, 1977; Lucor and Karniadakis, 2004; Zhao et. al. 2009; Zhou et al. 2009, 2011), our knowledge about vortex shedding and force characteristics of a cylinder with square cross-section inclined in an uniform flow is limited. This information is important in evaluating the hydrodynamic forces and vibrating frequency of the structures, which may shorten the fatigue life of the structures.
- Research Report > New Finding (1.00)
- Research Report > Experimental Study (1.00)
- Production and Well Operations > Well & Reservoir Surveillance and Monitoring > Production logging (0.68)
- Reservoir Description and Dynamics (0.46)